Pregnancy Weight Gain Calculator

If you are 18 or over, a healthy weight gain range can be calculated based on your pre-pregnancy body mass index (BMI). By staying within this range throughout your pregnancy you and your baby are more likely to be healthy. You will also be less likely to experience pregnancy and birth complications.

Body Mass Index or BMI is a frequently used method of measuring weight ranges in adults aged 18 years and over who are underweight, at a healthy weight, over a healthy weight (overweight )or way above a healthy weight (obesity). It is calculated by dividing weight (kg) by height (m) squared.

Gaining too much weight during pregnancy can increase your risk of developing complications such as gestational diabetes, high blood pressure, having a bigger baby and complications during birth. It also means there is a greater chance of your baby becoming obese during childhood and adulthood. If you are concerned about your weight, talk to your GP, health professional or enrol in the Get Healthy in Pregnancy Program to receive advice from a health coach.

Gaining too little weight during pregnancy can increase your risk of going into labour too early, having a baby that is smaller than expected and having problems breastfeeding your baby. It can also increase the risk of obesity and diabetes in your child. If you are concerned about your weight, talk to your GP, health professional or enrol in the Get Healthy in Pregnancy Program to receive advice from a health coach.

The calculator is based on the 2009 Institute of Medicine recommendations for weight gain in pregnancy. This is endorsed by the World Health Organisation and the National Health and Medical Research Council.

Only 5% of babies are born on their due date! Your first ultrasound gives the best indication of your due date. If your date changes, you can re-enter your expected due date in the calculator as many times as you like. This may change your healthy pregnancy weight gain range.

It doesn't have to be exact. Try and estimate your pre-pregnancy weight as best you can or ask your GP or health professional what they think it was. If you are below 14 weeks you should only have put on 2 kg, so this is a good place to start.

1. Place scales on a flat, hard surface (not on carpet)
2. Remove shoes and any heavy clothing
3. Step onto the scales and stand with both feet in the centre of the scale
4. Record your weight to the nearest 0.1kg

Don't have scales? Ask your midwife or doctor to be weighed at each antenatal visit

If you are under 18 it is recommended to see your GP or health professional about your healthy weight gain during pregnancy, and get regular dietary advice on what foods are best for you from a dietitian. The guidelines used in this calculator are targeted towards adults 18 and over. This is because your body composition and size is different to adults, and the adult measure of body mass (BMI) does not include under 18 year olds.

These results are based on the 2009 Institute of Medicine recommendations. Please note that recommended weight gain ranges are a guide and provide suggested limits rather than specific goals.

The Institute of Medicine recommendations for pregnancy weight gain only covers up until 40 weeks of pregnancy. You may continue tracking your weight gain on the calculator, but please consult your pregnancy carer for advice past your estimated due date.